1. Field Of Invention
The use of certain lactones or lactone reaction products as rust and corrosion inhibitors in hydrocarbon oil compositions is known. Thus, such a material as tetrapropenylsuccinic acid lactone has exhibited effectiveness as a rust inhibitor in gasoline.
The alkenylsuccinic acid lactones have been prepared by reacting an alkenylsuccinic acid with a hydrating mineral acid, such as 50 percent sulfuric acid, dilute hydrochloric acid or dilute sulfuric or phosphoric acid. In general, the reaction has been conducted at an elevated temperature ranging up to about 212.degree. C. and in the presence of a nonpolar solvent, such as hydrocarbon i.e. naphtha, kerosene or the like. A feature of the known process is that the catalyst for the reaction has been employed in a hydrating environment, i.e. in an aqueous solution, such as 50 percent aqueous sulfuric acid or other dilute aqueous mineral acids.
The conventional method for preparing a lactone reaction product is relatively inefficient and produces a low yield of the desired product. In particular, the conventional method gives a poor yield of a lactone reaction product in which the alkenyl radical on the alkenylsuccinic acid reactant is a high molecular weight radical having from about 300 to 3,000 average molecular weight.
2. Description Of The Prior Art
U.S. Pat. No. 3,248,187 discloses a hydrocarbon oil composition which has been inhibited against rust by the addition thereto of a lactone reaction product. This reference discloses the process of reacting an alkenylsuccinic acid in the presence of a dilute aqueous mineral acid and a hydrocarbon solvent at an elevated temperature to produce an alkenyl substituted lactone reaction product.